Notes on "Lucubrations of Twenty Years":
Blackstone, 1 Commentaries at *69, says:
But here a very natural, and very material, question arises: how are
these customs or maxims to be known, and by whom is their validity to be
determined? The answer is, by the judges in the several courts of justice.
They are the depositories of the laws; the living oracles, who must decide
in all cases of doubt, and who are bound by an oath to decide according
to the law of the land. Their knowledge of that law is derived from
experience and study; from the
"viginti annorum lucubrations" [lucubrations of twenty years] which
Fortescue mentions; and from being long personally accustomed to the
judicial decisions of their predecessors.
The reference in Blackstone to Fortescue, is to Sir John Fortescue,
De Laudibus Legum Anglie [In Praise of the Laws of England], chapter
8:
Wherefore, most gracious prince, you will be suffiently learned in the
laws of the Kingdom of England in a short time and with moderate industry,
provided you devote your mind to the apprehension of them. For Seneca said,
in a letter to Lucilius, There is nothing which great pains and diligent
care does not overcome. [Seneca, Epistle 50; Aucs. fo. 47]. Indeed I know the perspicacity of your mind,
and I dare say that in these laws, though the experience of them necessary
for judges is scarcely attainable in the labours of twenty years,
[viginti annorum lugubris] you will adequately acquire a knowledge fitting for a prince in one year.